ASTM A325 Structural Bolts
ASTM A325 was a standard for heavy Structural Bolts designed for steel-to-steel structural connections.
In 2016 ASTM A325, A325M, A490, A490M was withdrawn as International standard that previously covered heavy hex structural bolts are now grades under the new F3125 specification.
ASTM A325 defined the mechanical properties for heat-treated, quenched, and tempered bolts with a minimum tensile strength of 120 ksi, Size ranging from 1/2 to 1-1/2 inches in diameter.
ASTM A325 is the standard for structural steel Bolts in North America. ASTM A325 specifies heavy hex structural bolts for steel-to-steel connections in bridges, buildings, and other structural applications. These bolts are designed to be used with A563 nuts and F436 washers.
ASTM A325 covers high-strength structural bolts for structural steel connections in:
Building construction (AISC compliant)
Bridge construction (AASHTO compliant)
Other steel-to-steel connections requiring slip-critical or bearing-type joints.
- ASTM A325
- Finish: Plain Finish or Hot Dip Galvanized
- Thread: METRIC
ASTM A325
In December 2015, ASTM committee approved the new F3125 standard combined six structural bolt standards ASTM A325, A325M, A490, A490M, F1852, and F2280 to simplify and clean up inconsistencies within those various standards.
These high-strength bolts were used in structural connections for applications like bridges and buildings but are now covered by the updated ASTM F3125 specification.
Although technically any size ASTM A325 can be custom manufactured, there are certain restrictions as well as common lengths which are more readily available in the marketplace. Depending on the diameter, there may be longer lengths available.
| Diameters Allowed: | 1/2″ – 1-1/2″ |
|---|---|
| Available Lengths: | Up to 6″ – 10″ maximum (depending on diameter) |
| Available Finish: | Plain Finish or Hot Dip Galvanized |
| Origin: | Import or Domestic |
Bolt Length Tolerances
| Nominal Length, in. | Nominal Size, in. | |||
|---|---|---|---|---|
| 1⁄2 | 5⁄8 | 3⁄4 thru 1 | 11⁄8 thru 11⁄2 | |
| Thru 6 in. | -0.12 | -0.12 | -0.19 | -0.25 |
| Over 6 in. | -0.19 | -0.25 | -0.25 | -0.25 |
Structural Bolt Dimensions
Although the head dimensions for structural bolts are the same as any heavy hex headed fastener per ASME B18.2.6 2011, ASTM A325 heavy hex bolts have a shorter thread length than most other construction fastener grades.
Equivalent Standards
- ISO 898-1 (10.9)– Similar strength but different dimensions
- DIN 6914– German structural bolt (higher head dimensions)
- JIS B1186– Japanese industrial standard
- EN 14399-1 European Standard
. Advantages
✔ High shear strength for structural joints
✔ Reliable preload retention
✔ Available in corrosion-resistant types
✔ Widely available & standardized
| Bolt Diameter | D | F | C | H | T | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Body Diameter | Width Across Flats | Width Across Corners | Height | Thread Length | ||||||
| Max | Basic | Max | Min | Max | Min | Basic | Max | Min | Basic | |
| 1⁄2 | 0.515 | 7⁄8 | 0.875 | 0.850 | 1.010 | 0.969 | 5⁄16 | 0.323 | 0.302 | 1.00 |
| 5⁄8 | 0.642 | 11⁄16 | 1.062 | 1.031 | 1.227 | 1.175 | 25⁄64 | 0.403 | 0.378 | 1.25 |
| 3⁄4 | 0.768 | 11⁄4 | 1.250 | 1.212 | 1.443 | 1.383 | 15⁄32 | 0.483 | 0.455 | 1.38 |
| 7⁄8 | 0.895 | 17⁄16 | 1.438 | 1.394 | 1.660 | 1.589 | 35⁄64 | 0.563 | 0.531 | 1.50 |
| 1 | 1.022 | 15⁄8 | 1.625 | 1.575 | 1.876 | 1.796 | 39⁄64 | 0.627 | 0.591 | 1.75 |
| 11⁄8 | 1.149 | 113⁄16 | 1.812 | 1.756 | 2.093 | 2.002 | 11⁄16 | 0.718 | 0.658 | 2.00 |
| 11⁄4 | 1.277 | 2 | 2.00 | 1.938 | 2.309 | 2.209 | 25⁄32 | 0.813 | 0.749 | 2.00 |
| 13⁄8 | 1.404 | 23⁄16 | 2.188 | 2.119 | 2.526 | 2.416 | 27⁄32 | 0.878 | 0.810 | 2.25 |
| 11⁄2 | 1.531 | 23⁄8 | 2.375 | 2.300 | 2.742 | 2.622 | 15⁄16 | 0.974 | 0.902 | 2.25 |
Dimensions per ASME B18.2.6 2011 | ||||||||||